The present invention relates to clothes dryers. More particularly, the invention relates to a clothes dryer having a vacuum pump integral therewith to create sub-atmospheric pressures within the drum, thereby facilitating the drying of clothing and/or reducing the energy costs associated therewith.
The desire for time and energy conservation has led to many useful developments of household appliances. In particular, a clothes dryer with an integral vacuum source has been proven to be more energy efficient that a conventional clothes dryer. A directly proportional relationship between temperature and pressure allows the evaporation temperature of the water in the clothing to be reduced as barometric pressure within the dryer is decreased. This phenomenon provides many advantages, including reduced drying times and temperatures as well as less damage to clothing.
In the past, others have taken advantage of this phenomenon in an attempt to produce a more efficient clothes dryer. For example, U.S. Pat. No. 5,724,750 issued Mar. 10, 1998 to Burress (xe2x80x9cBurressxe2x80x9d) discloses a clothes dryer with infrared heating and vacuum drying capabilities in which a stationary vacuum pump is capable of reducing the vacuum pressure inside the drum to a sub-atmospheric pressure. Likewise, U.S. Pat. No. 4,057,907 issued Nov. 15, 1777 to Rapino et al. (xe2x80x9cRapinoxe2x80x9d) details an apparatus having a vacuum pump that reduces the air pressure within a chamber, while a microwave emitter excites the water molecules. The apparatus of Burress and Rapino, however, each employ a rotating shaft and/or bearing assembly at their interface between internal regions of atmospheric and sub-atmospheric pressure.
Unfortunately, Applicant has found that the embodiments exemplified by the prior art are extremely difficult to implement. In order to obtain the tight seal necessary for maintaining the apparatus"" internal vacuum, a soft bushing material, such as rubber or the like, must be utilized. Such a soft material, however, quickly wears, ultimately resulting in disintegration of the seal. On the other hand, hard materials that are impervious to wear are highly susceptible to tiny vacuum leaks, which in turn destroy the object of the invention.
It is therefore an overriding object of the present invention to provide a clothes dryer that incorporates vacuum assistance without the disadvantages inherent in the prior art. It is a further object of the present invention to provide such a clothes dryer that eliminates the need for a sealed bearing or rotating shaft extended between regions of atmospheric and sub-atmospheric pressure, thereby increasing the reliability of the appliance. Finally, it is an object of the present invention to provide such a clothes dryer that is economical to manufacture.
In accordance with the foregoing objects, the present inventionxe2x80x94a vacuum assisted dryer for accelerated drying of clothingxe2x80x94generally comprises a fixed frame, a rotatable drum within the fixed frame for holding and tumbling clothing within a vacuum sealable interior space, a vacuum source fixedly attached to the drum and a power delivery system for communicating electrical power from the fixed frame to the vacuum source on the drum. Preferably, the vacuum source comprises a vacuum pump and the power delivery system comprises a slip ring assembly about a spindle utilized to maintain the drum upon its axis of rotation inside the fixed frame.
In at least one embodiment, a plurality of heating pads are provided about the interior of the drum for imparting increased temperature to the clothing held therein, thereby further facilitating drying of the clothing. The heating pads may be conveniently located within paddles conventionally placed for the tumbling of clothing and may be powered through the same slip ring assembly as powers the vacuum source. A lint screen is also preferably interposed the vacuum source and the interior space of the drum, thereby preventing harm to the vacuum source from lint and the like.
The vacuum source exhausts to the interior space of the fixed frame, where moist air may be evacuated from the system with a blower assembly. The blower assembly maintains airflow from without the frame, about the interior of the frame and into and out of a duct to a conventional household dryer vent.
A vacuum relief for relieving vacuum pressure from within the drum is also preferably provided. Such a vacuum relief may comprises a valve in fluid communication with the interior space of the drum. In particular, Applicant has found suitable the use of a stopcock-type valve.
Finally, many other features, objects and advantages of the present invention will be apparent to those of ordinary skill in the relevant arts, especially in light of the foregoing discussions and the following drawings, exemplary detailed description and appended claims.